Multifrequency resonant network



Sept. 28 1926.

E. L. CHAFFEE Filed Mar ch 51, 1922 1Q X Y IIVVENTOR Sept. 28 1926,1,603,109

E. L. CHAFFEE v MULTI FREQUENGY RESONANT NET WORK Filed March 51. 1922 5Sheets-Sheet 2 INVENTOR E. L- CHAFFEE MULTIFREQUENCY RESONANT NET WORK-Sept. 28,1926. 1,601,109

Filed March 51. 1922 s Sheets-Sh eet INVENTOR \gaoyiwwy Sept, 28 ,1926.1 91 39 E. L. CHAFFEE MULTIFREQUENGY RESONANT NET WORK Filed March :51.1922 5 Sheets-Sheet 4 N N N S r 1 7 R 3 & m,

INVENTOR Sept. 28 1926. 1,601,109

E. L. CHAFFEE MI JLTIFREQUENCY- RESONANT NET WORK Filed March 31, 1922 5Sheets-Sheet 5 with improved efficiency,

26 and 28.

Patented Sept. 28, 1323.

amass stares r caries.

EMORY LEON CHAIFFEE, OF BELMONT, MASSACHUSETTS, ASSIGNOR TO JOEE HAYSHAMMOND, JR., OF GLOUCESTER, MASSACHUSETTS.

MULTIFREQUENCY BESONANT NETWORK.

Application filed March 31, 1922] Serial No. 548,538.

This invention relates to signaling systems and more particularly tosuch systems em loying a plurality of frequencies.

enie o'fthe objects of the present inven- 5 'tion are to provide animproved signaling system; to provide improved means for producingsimultaneously at least two oscillatory currents of unlike frequencies;to

provide means for producing such currents and for combining currents ofunlike frequencies derived from a plurality of sources and amplifyingsuch currents independently; to provide means forreducing interferencebetween parts of a coupled circuit network; and to provide otherimprovements as will appear from the following description taken inconnection with the, accompanying drawings.

- Referring to the drawings:

Figure 1 shows a portion, of a signalling system in which there isproduced in a coupled circuit network a plurality of currents of unlikefrequencies; Fig. 2 shows a modified form of the system of Figure 1employing tube generators;

Fig. 3 shows a transmitting station em-- p-loyingthe features of'theinvention and forming part ofa radiant energy signalling system;

Fig. 4 shows a modified form of the trans mitting station of Figure 3,using vacuum tube generators, and

Fig. 5 shows another modification in which oscillatory circuits areexcited directly by oscillating tubes.

Referring to the drawings and more particularly to Figure 1, oneembodiment of'my invention comprlsesa. plurality of sources ofalternating current of unlike frequencies, such as alternators 10, 11each coupled by means of a coil 12, 13 respectively -to a pair of poweramplifiers 14, 15. 'Each of these amplifiers consists of a usual, threeelement vacuum tube having a heatedfilament 17 forming a hot cathode, agrid 18 for controlling the passage of electrons, and a plate 19 uponwhich the electrons may impinge.

The circuit of the plate 19 of the amplifier 14 includes a pair ofinductances 27 and 25. Similarly the circuit of the plate of theamplifier 15 includes a pair of inductances The inductances 25 and 26to- -currents produced gether with a third inductance 22coupled thereto,may be consideredv as forming windings of a coupler 20. The inductances27- and 28 together with'an inductance 23 coupled thereto, may also beconsidered as forming windings of a coupler 21. The

couplers 20 and 21 have preferably substantially equivalent magnetic andstructural characteristics. The windings '22 and 23 are coupled togetherby means of a coupling which may take any desired form of inductive,capacitative or resistance coupling, that shown being an inductivecoupling 24 of cigventional type. I Suitable condensers 29 an 30 andresistancecoils 31 and 32 are included in the connections to the.coupling 24.

The connections of the windings 25,27, which are in .series, are such asto produce induced currents in the windings 22, 23 of the couplers 20,21 having predetermined relative polarities. winding 28 are similarthereto, and roduce with like primary increase or decrease, a secondarycurrent in the winding '23 having the same polarity as in the previouscase. The connections of the winding 26 are reversed "with respectthereto so that with a like primary increase or decrease a current ofopposite polarity is produced in the winding 22.

The connections of the The circuitc.ompr1sing the winding 22, I

condenser 29, etc. is designated .33, and the circuit comprising thewinding 23, condenser 30, etc. is designated 34. The circuits 33 and 34are arranged so that their induc tance and capacity constants and thecharacteristics of the couplin coil 24 cause them to .be resonanflto the'requencies of both by the alternators 10 and 11. When currents of theseselected frequencies co-exist in these coupledfcirc-uits, then for oneof these frequencies the currents in both parts are very closely inphase and for the other frequency they are very closely opposite inphase. Thus if for the frequency of the current produced by the source10 the current in'the circuit 33 is at 35 at its maximum posby the arrow36 at maximum positive value, at the same moment. For the frequency ofcurrent produced by the source 11, however, when the induced current isa maximum positive in circuit 33 as indicated by the arrow 37, it willbe substantially a maximum negative in circuit 34, that is, thedirection of current will be as indicated by the arrow 38. This propertyis not confined to networks of the specific form illustrated, but iscommon to many if not all circuits which have two natural periods ofoscillation. sometimes designated two degrees of freedom.

The energy imparted to the coupled circuits 33 and 34 through thewindings 25 and 27 from the amplifier 14, consisting of electric wavesof one of the selected frequencies to which the circuit networks 33 and34 are resonant, is transmitted thereto freely. Let it be assumed thatat a given moment the currents are flowing in the direction indicated bythe arrows 35, 36. The couplings provided to the amplifier 15 by thewindings 26, 28 are so connected, however, that waves of the frequencydelivered from the amplifier 14 do not appear in the plate circuit ofthe amplifier 15, the windings 26, 28 being connected so that thesecurrents op ose each other.

n the other hand, the energy imparted to the coupled circuits 33 and 34through the windings 26 and 28 from the amplifier 15, consisting ofelectric waves of one of the selected frequencies to which thesecircuits are resonant, is transmitted thereto freely. The direction ofthe currents of this different frequency is as indicated by the arrows37, 38 respectively, and since the connections of the windings 25, 27are as previously described, the effects of these Waves in the platecircuit of the amplifier 14 are substantially neutralized.

Thus it will be seen that substantially no interaction between thesources is produced, and that the respective power amplifiers operateindependently of each other, so that neither is subjected to currents ofany frequenc other than that which it is intended shall fie amplified byit. This condition of having only a single frequency to amplify is thecondition under which a high efiiciency, that is a high ratio of outputenergy to input energy, is obtained, with amplify lng devices of thischaracter, and this constitutes an important feature of my invention.Accordingly amplifier tubes 14. 15 of relatively great power can beemployed efficiently.

Referring to Figure 2 there is provided the same circuit network 33, 34as in the previous case, the current supply to the inductive couplings12 and 13 being obtained from a corresponding number of vacuum tubegenerators, such as 50, 51. Each of these includes a three-elementvacuum tube, such as 52, of conventional type, and a couplin 53 wherebythe plate circuit is coupled back to the grid circuit and regenerativeoscillations are obtained continuously.

The operation of the system of Figure 2 is similar to that described forFigure 1, with the exception that sources 50, 51 provide the energyused.

Referring to Figure 3, a transmitting station comprising the features ofthe invention includes a transmitting antenna- 101 connected 'to earth102 through the circuit 34 of the coupled network 33, 34, correspondingto the coupled network 33, 34 of Figure 1. A pair of sources ofalternating current of unlike frequencies, such as alternators 110, 111are inductively coupled by means of a pair of couplers 112, 113,respectively, to a pair of power amplifiers 114. 115. The circuit 116and its operations is substantially the same as that of network 16 ofFigure 1, like parts being designated by numerals having correspondingtens and units digits.

Thus in a manner similar to that described in detail for Figure 1,energy is transmitted to the coupled network 33, 34 from a plurality ofsources of alternating currents of unlike frequencies independently, andeach of these currents may be amplified by means of amplifiers ofrelatively high power, and at a great efficiency.

Referring in detail to Figure 4. this shows a transmitting stationcorresponding to the transmitting station of Figure 3, excepting that inplace of the alternators 110, 111 there is provided a plurality ofsources of current, such as 150, 151 each including an oscillatingvacuum tube 152. These are the same as in Figure 2, like parts beingdesignated by reference characters having like tens and units numerals.The arrangement is such that the oscillator 151 produces a frequencdifferent from that produced by the osci lator 150.

It is obvious that the transmitting stations of Figures 3 and 4 may beemployed as parts of systems for communication through the ether.Messages may be transmitted in any suitable manner. as for example, byinterrupting one of more of the sources of current.

The modified embodiment of the invention shown in Figure 5 comprises acircuit network 33, 34 as in Figure 2, the oscillatory circuits of thenetwork being excited directly by a pair of vacuum tubes 60 and 61. Acoupling 62 is provided for inductively coupling the plate and gridcircuits of the tube 60 to each other and to the inductances 25 and 27.Thus the tube 60 is connected for feeding back energy from its output toits input circuit, and the regenerative oscillations thereby producedare impressed upon the circuit network 33, 34 in the same mannor as wasdescribed previously in connection with Figures "1 and 2. Similarly, acoupling 63 is provided for inductively coupling the plate and gridcircuits of the tube 61 to each other and to inductances 26 and 28. Theregenerative oscillations thus produced are impressed upon the. circuitnetwork 33, 34 in the samemanner as described in connection with thecorresponding inductances 26 and 28 of Figure 1.

Suitable means suchas a tuning condenser 64 may be provided fordetermining the frequency of current produced by the tube 60 and its'associated couplings; and a similar means such as a condenser 65 ispro-- vided for the tube 61 and its associated couplings. The condenser65 is adjusted to a different value from that of the condenser 64, sothat currents of relatively different frequencies are produced.

The operation of the system of Figure 5, will be obvious from'theforegoing description taken in connectin with the description of theoperation of Figure 2. It will be seen "that. oscillatory currents ofunlike frequencies are produced, and these are independently impressedupon the network 33, 34, and allowed to coexist therein, their valuesbeing coincident respectively with the two natural frequencies of thecoupled network 33, 34.

Thus it will be seen that I have provided a simple and economical meansfor independently generating two currents and applying them to a singlenetwork without having either current affect the generation of theothercurrent. By this means substantially no reaction on either source ofcurrent exists due to the generation of current by the other source. 7

Furthermore, two sources of alternating currents of differentfrequencies may readily and efliciently be held-at constant difference,that is, although their periodicities may vary slightly due tounavoidable variations in the operation of the sources, the differencemay be held substantially constant.

It is to be noted that in the embodiments of Figures 3 and 4, theamplitude of the combined currents of different frequencies is at aminimum in circuit 33 when it is at a maximum in circuit 34 and viceversa. Accordingly the point of energy. dissipation is shifted from oneportion (33) of the coupled network to the other portion (34)alternately, the action of the energy sources remaining substantiallyconstant.

The construction illustrated sider to be the preferred embodiment ofmyinvention and it is therefore to be distinctly understood that I do notlimit'myself there: to as many changes may be made in point of detailand other embodiments, resorted and described herein is merely what Inow con so 'tro-motive forcesof substantially equal value and opposingone another.

2. A system for the. production of oscillatory energy comprisinga-circuit network, means co nprising a regenerative vacuum tube forimpressing upon said network at a pair ofv spaced portions thereof apair of substantially synchronous, oscillating,

electro-motive forces of substantially equal value and mutually aiding,and means comprising a' regenerative vacuum tube for impressing-uponsaid network at a pair of spaced portions thereof and in oppositerelations a second pair of substantially synchronous, oscillating,electro-n'iotive I forces of substantially equal value and of afrequency different from that of the first-mentioned electro-motiveforces.

3. A system for the production of oscillatory energy comprising acircuit network, a three-electrode, electron emitting device, means forcoupling the output circuit of said device to said network at'a pain ofspaced portions thereof in a' manner to impress thereon a pair ofsubstantially synchronous, oscillating, GlGCtIO-lIlOtlVG forces a ofsubstantially equal value and, mutually aiding, a secondthree-electrode, electron emitting device, and means for coupling theoutput circuit of said second device to said network at a pair of in amanner to impress thereon a second pair of oscillating, electro-motiveforces of substantially equal value and opposing one another.

latory energy comprising a circuit network,

means comprising an electron emitting device connected for continuousregeneration and an amplifier for amplifying the currents produced bysaid regeneration for 1mof spaced portions there'- 4. A system for theproduction of oscilpressing upon said network at a pair of spacedportions thereof a pair of substantially synchronous, oscillating,electro-motive forces of substantially equal value and mutually aiding,and means comprising an electron emitting device connected forcontinuous regeneration and an amplifier for amplyfying the currents.produced by saidregeneration for impressing upon said neti work at apair of spaced portions thereof a second pair of oscillatingelectro-motive forces of substantially equal value and opposing oneanother.

5. A system for the production of oscil latory energy comprising acircuit network including two, inter-coupled circuits each havinginductance and capacity, means comprising a three-electrode, electronemitting device and like couplings between the output circuit of saiddevice and the network for impressing upon said network at a-pair ofspaced portions thereof a pair of substantially synchronous,oscillating. electromotive forces of substantially equal Value andmutually aiding, and means comprising a second, three-electrode electronemitting device and reversely-arranged couplings between the outputcircuit of said second device and the network for impressing upon saidnetwork at a pair of spaced portions thereof and in opposite phaserelations a second pair, of oscillating electro-motive forces ofsubstantially equal value and of a frequency different from that of thefirstmentioned electro-motive forces.

6. A system for the production of oscillatory energy comprising acircuit network, means comprising an electron emitting device connectedfor producing oscillations of a predetermined frequency and a secondelectron emitting device for amplifying the currents produced by saiddevice for impressing upon said network at a pair of spaced portionsthereof a pair of substantially synchronous oscillating electro-motiveforces of substantially equal value and mutually aiding, and meanscomprising a third electron emitting device connected-for continuouslyproducing oscillations of a relatively different frequency, and anadditional electron emitting device for amplifying the currents producedby said third named electron device for impressing upon said network ata pair of spaced portions thereof a second pair of oscillatingelectro-motive forces of substantially equal value and opposing oneanother.

7 Apparatus for producing oscillating current comprising a plurality ofcouplers each having a plurality of windings, a source of oscillatingcurrent of a predetermined frequency, an amplifier for amplifying saidcurrent, said source and amplifier being operatively connected to awinding of each of the couplers, a second source of oscillating currentof relatively different frequency. a second amplifier for amplifyingsaid second current, said second source and second amplifier beingoperatively connected to a second winding of each of the couplers, and anetwork composed of inter-coupled circuits and including a third windingof each of the couplers, the connections of at least one of the windingsof one of the couplers being unlike the connections of the correspondingwinding of the other coupler. Y

8. Apparatus for producing oscillating current comprising a plurality ofcouplers each having a plurality of windings, a source of periodicimpulses of a predetermined frequency, an amplifier for amplifying saidimpulses, said source and amplifier being operatively connected to awinding of each of the couplers, a second source of periodic impulses ofrelatively different frequency, a second amplifier for amplifying saidsecond named series of impulses, said second source and second amplifierbeing operatively connected to a second winding of each of the couplers.a network composed of two. inter-coupled circuits and including a thirdwinding of each of the couplers, the connections of one of the firstnamed windings of one of said couplers being reverse with respect to theconnections of the corresponding winding in the other coupler.

9. A system for transmitting radiant energy comprising a circuit networkresonant to currents of two frequencies and including two, inter-coupledcircuits each having inductance and capacity, means for impressing uponthe network at two portions thereof spaced apart substantiallysynchronous,

alternating, electro-motivc forces of one of said frequencies, theinstantaneous values of the currents produced in the respective portionsof the network by said electro-motive force being substantially equaland of like. phase, and means for impressing upon the network at twospaced portions thereof additional substantially synchronous,alternating, electro-motive forces of the other of said frequencies, theinstantaneous values of the currents produced in the respective portionsof the network by said second named electro-motive forces beingsubstantially equal and opposing.

10. A system -for transmitting radiant energy comprising a circuitnetwork resonant to currents of two frequencies. meansincluding athree-electrode vacuum tube for impressing upon the network at twoportions thereof spaced apart periodically varying electro-motiveforces, the instantaneous values of the currents produced'in therespective portions of the network by said electro motive forces beingsubstantially equal and aiding, and means including a three-electrodevacuum tube for impressing upon the network at two spaced portionsadditional periodically varying electro-motive forces having arelatively different frequency, the instantaneous values of the currentsproduced in the respective portions of the network by said second namedelectro-motive force being substantially equal and opposing.

11. A system for producing oscillatory energy comprising a plurality ofsources of frequencies, and means for impressing said impulses upon the,network, including couplings reversely arranged to prevent currentimpulses of one of saidfrequencies from reacting on the source ofimpulses of theother of said frequencies.

- 13. A- system for transmitting radiant energy comprising a pluralityof sources of periodic impulses of unlike frequencies, a circuit networkresonant to a plurality of frequencies and means for impressing saidimpulses upon the network comprising reversely arranged inductivecouplings preventing current impulses of one of said frer quencies fromreacting through the network upon a source of impulses of another ofsaid frequencies, 1 a

14, A system for transmitting radiant energy comprising two sources ofperiodic impulses of unlike frequencies, a circuit nettov both of saidfrequencies and including two inter-coupled circuits each havinginductance and capacity, means for impressing said impulses upon thenetwork comprisingreversely arranged couplings for preventing currentimpulses of one of said frequencies from reactingupon the source ofimpulses of the other of said frequencies, and means operativelyconnected with the network for impressing energy upon the ether.

15. A system for transmitting radiant energy comprising a pair ofsourcesofalternating currents of unlike frequencies, a circuit networkcomprising a pair of coupled oscillatory circuits, and reverselyarranged couplings for impressing said currents upon thenetwork soas tosubstantially neutralize work resonant the tendency 'for one of saidcurrents to react through the net work on the source of current ofdifferent frequency.

- 16. A system for producing oscillatory currents for systems ofcommunication comprising a circuit network including two, inter-coupledcircuits each having inductance 1 and capacity, means for impressingupon said network "at difierent portions thereof two substantiallysynchronous oscillating electro-motive forces of substantially equalvalue, andmeans for impressing upon said network at two other differentportions thereof a secondpair of oscillating electromotive forces ofsubstantially equal value,

the phaserelationshipbetween said pairs of electromotive forces beingsuch that energy is impressed alternately upon the two differentportions of the net work.

17. A system for the production of oscillatory energy comprising acircuit network including two inter-coupled circuits each havinginductance and capacity, means for impressing upon said network at twospaced portions thereof substantially synchronous, oscillating,electro-motive forces of substantially equal value and like phase, andmeans for impressing upon said network at two spaced portions thereofand in opposite phase relations two substantially synchronous, osvcillating, electro-motive forces of substantially equal value and of afrequency different from that of the first-mentioned electro-motiveforces. A

18. A system for the production of oscillatory energycomprising acircuit network including two inter-coupled circuits each havinginductance and capacity and one of said circuits containing an antennaand ground, means for impressing uponsaid network at two spaced portionsthereof substantially synchronous oscillating electro-mot'ive forces ofsubstantially equal value and like phase, and means for impressing uponsaid network at two spaced portions thereof and in opposite phaserelations two substantially synchronous oscillating electro-motiveforces of substantially equal value and of a frequency diiferentfromthat of the first-mentioned electro-motive forces.

19. A system for-the production of oscillatory energy comprising acircuit network including two circuits inductively coupled together andeach containing inductance and capacity, means for impressing upon saidnetwork at two spaced portions thereof substantially synchronousoscillating electromotive forces ofsubstantially equal value and likephase, and means for impressing upon said network at two spaced portionsthereof and in opposite phase relations two and of a frequency differentfrom thatof the first-mentioned electro-motive forces.-

20. A system for the-production of oscillatory energy comprising acircuit network including two inter-coupled circuits each havinginductance and capacity, means for impressing upon saidnetwork at twospaced portions thereof substantially synchronous oscillatingelectro-motive forces of substanti ally equal value and like phase,means for impressing upon said network at two spaced portions thereofand in opposite phase relations two substantially synchronousoscillating electro-motive forces of substantially equal value and of afrequency different from that of the first-mentioned electro-motiveforces, and means connectedwith said network .for radiating energy intothe ether.

21. A system for the production of oscillatory energy comprising aplurality of sources of electro-motive force of different frequenciesrespectively, a circuit network resonant to currents of a plurality ofsaid frequencies and comprising two, inter-coupled circuits each havinginductance and, capacity and one containing an antenna and ground, meansfor impressing upon said network at two spaced portions thereof and fromone of said sources substantially synchronous, oscillating,electro-motive forces of substantially equal value and like phase, andmeans for impressing upon said network at two spaced phase relations twosubstantially synchronous, oscillating electro-motive forces fromanother of said sources and of substantially equal value.

portions thereof and in opposite 7 22. A system for the production ofoscillatory energy comprising two sources of electro-motive force of twodifferent frequencies respectively, a circuit network resonant tocurrents of said two frequencies and comprising two inter-coupledcircuits, means for impressing upon said network at two spaced portionsthereof and from one of said sources substantially synchronous,oscillating, electro-motive forces of substantially equal value and likephase, and means for impressing upon said network at two spaced portionsthereof and in opposite phase relationtwo, substantially synchronous,oscillating, electro-motive forces from another of said sources and ofsubstantially equal value.

Intestimony whereof I hereunto afiix my signature.

, EMORY LEON CHAFFEE.

